Trimmer



Feb. 24, 1942. F. PELRNACIK EIAL 2,274,561

TRIMMER Filed E65: 10, 1941 8 Shveets-Sheet 1 I INVENTORS FRANK PERNACKOHULTE WILLIAM A- r 7 f; ATTORNEKS Feb. 24,1942, F. PERNACK ETAL;

TRIMMER Filed Feb. 10, 1941 8 Sheets-Sheet 2 ll I? h INVENTORS FRANKPERNACK WILLIAM SOHU TE BY WWW! ATTORNEYS F b-24,1942. F. PERNAK m2,214,561

mm, W 1 ATTORNEYS Feb.- 24, 1942.

I F. PERNACK ETAL TRIMMER Filed Feb. 10, 1941 I 8 Sheets-Sheet 4INVENTORS K PERNACK N LIAM A. SCHULTE ATTORNEYS Feb. 24, 1942. E2,274,561

, TRIMMER Filed Feb. 10,1941 8 Sheets-Sheet 5 97 I06 .A 74 96 I03 3flaw/ll; 4

v,.,,.-n\\w 35* 10 um n E F rw7l FIG-.8. 1' 83 I "1;" M ".1 i W M W l 11as i I INVENTORS FRANK PERNAOK WILLIAM A. SCHULTE WM W Feb. 24, 1942.

F. PERNAc'K ETAL' TRIMMER Filed F sh. 10, 1941 8 Sheets-Sheet 6INVENTORS FRANK PERNACK BY W I L IAM SCHULTE FIG-.Il.

ATTORNEYS Feb. 24, 1942.

FQPgRNACK ETAL TRIMMER Fiied Feb. 10, "1941 8 Sheets-Sheet 7 I INVENTORSFRANK PERNACK BY W 'WILLIAM A. iCHULTE Y z ATTORNEYS work piece andPatented Feb. 24, 1942 UNITED PATENT OFF ICE TBIMLMER Frank Pernack andWilliam A. Schulte, Detroit, Mich., assignors to National Broac'h &Machine Company, Detroit, Mich., a corporation of Michiga'n ApplicationFebruary 10, 1941, Serial No. 378,311

- 12 Claims. (Gl. 125-11) I employs a template accurately formed inaccordance' with the profile which is to be ground on the teeth of thegear, breach or the like. Trimming mechanism for use with the type ofgrinding machine in which the grinding wheel has the desired profile ofthe teeth accurately formed thereon, which is reproduced on the teeth ofthe gear, broach or the like by passing the grinding wheel axially ofthe gear-,broach or the like. In other words, the. grinding machine-isof the'type in which a complementary profile is formed on thegrinding'wheel, rather than of the type in which the profile of theteeth on the work piece is generated.

Trimming mechanisms for trimming the desired curvature or shape onto agrinding wheel from a template form have long been employed. One of theserious difliculties of this type of trimming mechanism in the past hasbeen that no provision has been made for adinvolute shape and itsnearest true radius likeness. This system allows the diamonds to be used7 until they no longer present asuitable cutting edge without causinginterference in duplicating accurately and thus increasing the usefullife of the diamonds many times and not disturbing the "set-up for amuch longer period.

' According to the present invention, trimming mechanism is adjustableso that the lever arm which carries the diamond point may have itseffective length adjusted to be approximately tially adjacent'theaveragecenter of curvature. of the surface. As a result of this, the lever armwhich carries the diamond point is always subvstantially perpendicularto the surface being trimmed at its point of engagement. This results insubstantially increased life of the diamond trimmer-,ahd in practice wehave observed justing the trimming mechanism'in accordance with thecurvature of the shape being ground on the wheel so that the armwhichcarries the trimming point may at all times be substantiallyperpendicular to the-surface being trimmed at the point of engagement.

For ,the most part, work pieces which.have

given most trouble in the past have been those having an involute formthat have a great degree of angulardifierence between extremeperpendiculars.

the very accurate surface of the template be exactly the same shape asthat of the diamond trimmer point in order to duplicate within therequired manufacturing tolerances. It may be readily seen that a slightamount of (wear on the diamond point in this case produces error in thenecessitates early replacement of diamonds.

X In so arranging and shaping the principle parts 7 herein described,incur invention, namely the form covered in Figures 5 to10, it ispossibie'to maintain a point or axis so located as to permit point (oraxis) and yet have provision for mov-# -ing or floating. this said point(or axis) sufli that when the present invention is practiced the lifeofthe trimmer is several times the life of anism.

It is a further-object of the invention to provide, trimming mechanismhaving means for adjusting theeflective length of the lever arm carryingthe diamond point so that said lever arm is substantially equal to theaverage radius of curvature of the surface being trimmed.

It is a further object of the invention to provide trimming mechanismhaving adjustments which result in locating the pivot point of the leverarm carrying the diamond point substantially ad jacent the averagecenter of curvature of the A surface being trimmed.

. It is a further object of the invention to proe Q videtrimmingmechanism employing a .template and a compound lever system in which thepivot points of the levers and their lengths are adjustable.

' 'to provide a trimming mechanism employing a the diamond point torotate freely about this 3 template in which a system of compound leversis employed, the pivot point of one of said levers being located at theopposite side of the template from thesurface being'trimmed. 1

It is a further object of the present invention to provide a trimmingmechanism having a pair of trimming devices alternately shiftable tooperative and inoperative position.

It is a further object of the invention to provide a trimming mechanismhaving a .pair of simultaneously operable trimming devices.

Other objects of the invention will be apparent as the descriptionproceeds, and when taken in conjunction with the accompanying drawings.wherein: Y

Figures 1 to 4 are diagrammatic views illustrating the relationshipbetween the trimming arm and the trimming wheel; I

Figure 5 is a side elevation of one form of trimming mechanism;

Figure 6 is an end view of the trimming mechanism shown in Figure 5 withparts broken away;

Figure 7 is a plan view of the trimming mechanism shown in Figure 5 withparts broken away;

Figure 8 is a section on the line 8-8, Figure 7 Figure 9 is a section onthe line 9-9, Figure 5 Figure 10 is asection on the line Ill-I0, Figure5; I

Figure 11 is aside elevation of a modified form of trimming mechanism;

Figure 12 is an end view of the trimming mechanism shown in Figure 11with parts broken away;

Figure 13 is a plan view of the trimming mech-- anism shown in Figure11;

Figure 14 is a section on the line I4I4, Figure 11;

Figure 15 is a section on the line I5I5, Fig- I ure 11; and

Figure 16 is a section on the line I8I6, Figure 11.

Referring first to Figures 1 to 4, we have illus-. trated in Figure '1 aportion of a grinding wheel IIJhaving its periphery trimmed to provideinvolute surfaces II and I2. The diamond point I3 is mounted on anadjustable element I4 which is axially adjustable of a sleeve. I5. Thesleeve I5 is connected to a lever arm I6 indicated by the broken linewhich is pivoted to a pivot point I1, and the-pivot'connection'betweenlever arm I6 and the sleeve I5 is indicated at l8. It will be observedin Figure 1 that the point I8 is located substantially adjacent theaverage center of curvature of the surface I2, and the diamond point I8is spaced from the pivot point I8 a distance vature of the surface I2.As a result, the axis ,of the lever arm carrying the diamond point I3(as determined by the line joining the diamond point I3 to the pivotpoint I8) willalways be approximately perpendicular to the surface I2 atthe point of contact. This will result in a uniform action on thediamond point and will substantially lengthen the life of the diamond.In addition. since in practice it is impossible to provide a diamondpoint I3 which is a theoretical point, this same construction providesfor accurate reproduction of the curve. In other words, if the attitudeof the diamond were changed relative to the surface which it is trim--ming, errors would be introduced into this surface by reason ofirregularities in the diamond trimmer. By maintaining the lever armcarry-' thereon by a diamond point I3 carried by the element II which islongitudinally adjustable 'in the sleeve I5. Since the average radius ofcurvature of the surfaces 2| and 22 is substanture of the surface 22.

tially longer in the wheel 28 than in the wheel III, the element I4 willbe adjusted outwardly in the sleeve I5 so as to locate thefpoint I8substantially adjacent the average center of curva- At the same time itwill .be necessary to relatively adjust the wheel and the trimmingmechanism so as to locate the pivot point I! substantially closer to theaxis of the wheel 20. In Figure 2 we have illustrated tlus condition asbeing taken care of by adjusting the trimming wheel downwardly. Inpractice, how-' ever, it is ordinarily preferable to adjust the pivotpoint H of the lever I6 upwardly relative to the ax'is'of the wheel 20.

In Figure 3 we have indicated a trimming wheel 30 having curves 3| and32 trimmed thereon by the diamond I3 of the element ll. In this case theelement I4 is adjustable longitudinally of the sleeve I5 so as to locatethe point I8 substantially further from the diamond point I3. The pointI8 is located substantially-adjacent the average center of curvature ofthe surface 32, and for this purpose a further adjustment of the pivotpoint I! of the lever I6 relative to the wheel 80 is made. 1

In Figure 4 we have indicated a wheel 40 having surfaces ll and 42 ofsubstantially larger radius of curvature, as shown in Figures 1 to 3. Inthis case the diamond point I3 of the element I4 is adjusted further outof the sleeve I5 so as to locate the pivot point I8 substantiallyadjacent the center of curvature of the surface 42. A sec and adjustmentis made which positions the pivot point II of the lever I6 substantiallycloser to the axis of the wheel ,lll thuspositioning the pivot point I8at the desired location.

In' these figures it will be noted that the pivot point I1 of the leverI6 is located at the opposite side of the wheel from the surface beingtrimmed.

This is a desirable condition since it permits the lever formedbetweenthe sleeve I5 and diamond I4 to swing freely about the pivot point I8 inboth extreme positions of movement. If on the located at the same sideof the wheel as the surface being trimmed, there will be a tendency tobind in some cases, where lever I8 and sleeve I5 approach a straightline. This is particularly true when a small radius of curvature istrimmed onto a wheel, as illustrated in Figure 1. In this ure it will benoted that in the two extreme positions shown by full and dotted lines,the axis of the lever .arm I6 shown between sleeve I5 and is acted uponby the grinding wheel. Grinding.

machines, of this type are well-known and normally ,the slide istraversed in the line of the work axis between a working position inwhich the work piece is located at the grinding wheel, and a trimmingposition in which the trimming mechanism is located at the grindingwheel.

In the type of trimming device chosen to illustrate the presentinvention.- the template has a shape identical with the shape to betrimmed 'onto the periphery of .the grinding wheel. In

other words, the compound system of levers reproduces the curvature ofthe template at a one to one ratio. It is further a feature of thepresent invention that the follower point which engages the surface ofthe template is aligned with the diamond point which trims the surfaceof the grinding wheel. Accordingly, the template will 1 position onthesli'de 59. Lateral adjustment of the base 5| on the slide 59 by meansof adjustable bolts 56 and 51, these being calibrated as. I indicated at58 to provide for ease in positioning the base 5 I, is provided.

The base 5| is provided with a pair of vertical guide posts 69 whichare, rigidly supported in the base 5|. A trimmer frame indicatedgenerally at 62 is provided with a pair of apertured guides 63 and 64which engage the posts 69 and provide for vertical adjustment of thetrimmer frame 62 thereon. The guides 63 and. 69 have internally threadedbosses 65 and 66formed thereon for the reception of clamping meansindicated in Figure 5 at 61. These clamping means lock thetrimmer frame62 in the desired position of vertical adjustment. I

Secured to the trimmer frame 62 is a vertically extending arm 19 whichcarries the template ,T in vertically adjustable position thereon. The

structure of the template supporting'mechanism is best illustrated inFigures 8 and 9,'in which the arm 19 is shown as provided with avertically extending slot 1|." Vertically adjustable in the slot H is ablock I2 having flanges 19 engaging the surfaces of the arm 19 adjacentthe slot 1| and having its main body portion received within the slot1|. A plate 14 is bolted or otherwise secured to the block 12 asindicated 'at 15, the plate 14 engaging surfaces of the arm 19 atopposite sides of the slot H from the surfaces engaged by theflanges 13.This locatesthe block 312 accurately in the slot 1| but permits verticaladjustment thereof by means which will now be described. r I e- I Thearm 19 adjacent its top has an apertured boss 16 which receives anadjusting bolt 11. The

bolt 11 is provided with a squared upper portion 19 to be engagedby awrench or suitable tool, r

and is further provided with a flange 19 which rests upon the flat uppersurface of the boss 16, I

thus limiting downward movement of the bolt 11. A retaining cap 89engages over the flange .19 and is secured in place by bolts 8|, as besttation of the bolt 11 results in vertical adjustmentor the block 12 andits associated structure.

A look bolt 93 is adapted to engagethe adjustable bolt 11 to'lock thesame in adjusted position.

The block 12 has an accurately formed flat surfaced boss 94 againstwhich the template T is of collars I96 and I91 which cooperate with apasses through another opening in the template T and clamps the templatein accurately located position against the flat surface of the boss 64.

As previously stated, it is essential in the present construction thatthe template T be located at a definite position aligned with thesurface of the grinding wheel at the point of trimmin and aligned alsowith the correspond- .ing surfaces of the work piece being ground. In

order to position the template T in the proper position, it will beevident that it is necessary to adjust the trimmer frame 62 verticallyand to make a corresponding vertical adjustment of the block 12 carryingthe template T. By this arrangement it 'will be possible to' positionthe template T in properly aligned position while the' trimmer frame 62is located in various positions of vertical adjustment.

The trimmer frame 62 is provided with a pair of aligned openings 99 forreceiving pins 9|. The pins 9| form the pivot supports for the system oflevers which carry the diamond trimmers and, accordingly, their axescorrespond to the pivot point I1 shown in the diagrammatic. views ofFigures 1 to 4. Lever structures 92 and 93, best seen in Figure 6, arepivoted to the pin 9 I. The lever structure 92 comprises asleeve 94embracing corresponding pin 9| and carrying a pair of arms 95 which, inturn, support a second sleeve 96. The sleeve 96 supports a diamondcarrying supporting shaft 91 and a follower member 96 having a tubularportion 99 which are assembled together to form thesecond lever of thecompound lever system, as best illustrated in Figure duced portion I99over which the member 99 fits.

A positioning collar IN is located within the sleeve 96 and abutsagainst the shoulder I92 of the shaft 91. A lock screw I99 retains thepositioning collar I9I in the sleeve 96 and the end of the tubularportion 99 engages the collar lol so that the lever formed by themembers 91 and 99 is retained accurately against axial displacement inthe sleeve 96.

The member 99 is retained in assembled position on the shaft 91 by meansof awasher I99 which, in turn, is retained in position by mean of a setscrew I95.

As best seen in Figure 10, rotation of the shaft 91 and member 99 islimited by means of a pair stop pin I99 let into a boss in the sleeve96. The collars I96 and I91 are clamped in position on the tubularportion 99-by means of set screws I99 andi I9. The collars have cutawayportions indicated at III providing shoulders II! which are adapted toabut stop. pin I96 to limit rotation of the parts. By adjusting-thecollars I96 and I'91 it will .be possible to limit the amplitude ofrotation permitted the shaft 91 and the, member 99 in either direction.

As previously stated, it is desirable to adjust the I effective lengthof the lever arm terminating in the diamond point I! and thecorresponding point of the follower F. Accordingly, theishaft 91 isoffset, as indicated in Figure 8 so that its to be positioned.Positionin pins 65 are pro- Vided, and the template T-is provided with 90 curately located openings for receiving the pins sleeve portion. II5,.in which thediamond element H9 carrying the diamond point II3,permits location of the point II! very close to the axis of rotation ofthe shaft'91. An adjusting screw I29 is provided in the sleeve portionH6, and a lock screw I 2| retains the diamond element Ill in adjustedposition.

correspondingly, at the opposite end aof the shaft 91 the element 98 isofl'set from the axis of the shaft 91 and tubular portion 99 so as topermit "the point of the follower F to be located substantially adjacentthe axis of the shaft 91. The follower is adjustable in an opening I22in the member 98, and an adjusting screw I23 is provided for adjustingthe follower F in the opening I22. A suitable lock screw (not shown) isalso provided, similar to the screw I2I co.- operating with the diamondelement I I4.

We have so far described in detail the construction of the compoundlever structure 92 and its associated mechanism. The leverstructure 93is substantially similar, with the exception that its lever arms 95, asbest seen in Figure 7,

are located so as to be received-between the lever,

arms 95. This is a structural arrangement to avoid interference betweenthe two lever systems.

The trimming mechanism illustrated in Figures to is adapted to trim oneside of a grinding wheel at a time and, accordingly, the

lever structures 92 and 93 are alternately movable to operative andinoperative position. This is best illustrated in Figure 6 in which thelever structure 92 is shown in operative position and the leverstructure 93 is shown in inoperative position. In order to retain theselected system in operative position, each of the systems has dependingprojections I30 having seats I3I for the reception of the end of aspring pressed plunger I32. The spring pressed plungers I32 are locatedin adjustable housings I33 threaded within bosses I34 of the trimmerframe 62. Compression springs I35 seat against shoulders I36 in themember I33 and at their opposite ends bear against collars I3I formed onthe plunger I32. As will be evident from Figure 6, the plunger I32 tendsto rotate the lever structures 92 and 93 into operative position.

' In order to move either of the lever systems 92 or 93 into inoperativeposition, dogs I40 are provided which are pivoted to the trimmer frame62 as indicated at I4I. Each of the dogs I40 has an actuating lever I42secured thereto for swin ing the same. The lever structures 92 and 93are each provided with upwardly extending projections I43 which areadapted to cooperate with the dogs I40. As shown inFigure 6, the leverstructure 93 is retained in inoperativeposition by its dog I40 engagingthe projection I 43. The lever structure 92 is retained in operativeposition, its dog I40 being withdrawn from engagement with itsprojection I 43 so as to permit the lever structure 92 to be swungcounterclockwise about the axis of the pin 9| under the influence ofthespring pressed plunger I 32.

The trimming operation is carried out by means of an actuating leverI50, as shown in Figures 7 and 8. The actuating lever I50 is rigidlysecured in a suitably formed opening, in the member 98 and'locked inplaced by a set screw,

in the direction to retainthe point of the fol-- their axes and willalso result in a s ght rotation of the lever system 92 or 93 about theaxis of the pin 9I. The point of the diamond II3 being aligned with thepoint of the follower F, it will trace a curve identical with thecurvature on the template F and will thus reproduce this curvature onthe periphery of the grinding wheel in a well-known manner.

As stated at the outset, the structure is adjustable to position thepivot center of the diamond I I3 substantially adjacent the averagecenter' of curvature of the surface being trimmed. Specifically, thisadjustment is made by adjusting the diamond carrying element II4radially of the shaft 91 and making a like adjustment of the follower F.This provides for making the length of the pivot arm of the diamond II3substantially equal to the average radius of curvature of the surfacebeing trimmed. The length of this pivot arm is, of course, the radialdistance between the point I3 and the axis of the shaft 91; A furtheradjustment is necessary to position the axis of the shaft 91substantially adjacentthe average center of curvature of the surfacebeing trimmed. This is taken care of by positioning the trimmer frame 62vertically .of

the posts 60 to the desired position, and makes a correspondingadjustment of the template T so as to position the same in alignmentwith the periphery of the trimming wheel.

By employing the mechanism illustrated in Figures 5 to 10, it will benecessary to trim first one side of the wheel and then the other side,since the lever structures 92 and 93 are arranged for alternate use. Itwill be observed in Figure 6 that the pivot axis of the pins 9| arelocated on opposite sides of the template and grinding wheel from thesurface being trimmed. However,

in some cases, this desirable feature may not be necessary and theconstruction may be modified so as to provide for simultaneous trimmingof opposite sides of the grinding wheel.

Such a construction is illustrated in Figure:- 11 to 16.

In this second modlflcationwe provide a subbase 200 which is adapted tobe mounted on the work-carrying slide of the grinding machine, a

a removable gib 20I being provided for this purpose. Adjustably securedon the sub-base 200 is a base 202 which is adjustable transversely ofthe sub-base so as to position the template in line with the workcenters of the grinding machine. The base 202 and sub-base 200 haveinterfitting ways, as indicated, at 203 in Figure 11, which permitstransverse sliding of the base 202. At each side of the base 202; asbest seen in Figure 12, are a pair of depending ears 204 having threadedopenings for the reception of adjusting bolts 205 which bear againstside surfaces of the sub-base 200. By loosening one of the bolts 205 andtightening the other a corresponding amount, the base 202 is adjustedtransversely. Clamp bolts 205' are provided for clamping base 202 inadjusted position. At 201 we haveindicated lines carried respectively bythe sub-base and adapted to register with each other when the base is inthe proper position of adjustment.

lower F in engagement with the surface of the template T. Since thissurface is not an arc of circle, swinging of the lever I50 will resultin rotation of the shaft 91 and member 98 about A more accurateindication of the accuracy of the adjustment of the base is provided byindicator 209, shown in Figure 13, assembled with the detailedconstruction best seen in Figure 16. The indicator'208 is mounted insleeve 209 seated in recess 2I0 formed in base 202, and retained indefinitely-located position therein by a set pass through slots 221.

screw 2 engaging recess 2| 2 in the sleeve 2l0.

The indicator 208 is of conventional type and includes a projecting arm2l3 adapted to actuate the indicator-mechanism. Mounted on the subbase200 is a'pin 2l4 having a gauge surface 5 215 adapted to engage theindicator actuator 2l3. When the trimming mechanism is initiallycalibrated the dowel pins which support the template (later to bedescribed) are accurately aligned with the work centers, and the sleeve209 is positioned so that the indicator needle 2l6 has an intermediatereading. The recess H2 is then provided and the set screw 2 is seatedtherein. The calibrations 201 would only be used for an-approximatesetting.

The indicator is used in making minute corrections iii-relative radialpositions of the template to the'work piece, this being accomplished bymoving the base transversely until the center line of the templateintersects the work center.

This adjustment should be very small andis only necessitated inmisalignment resulting from wear on gauge points, etc.

Thus in the event that template T is for some reason slightly inclinedfrom the vertical axis,

it will be possible to shift the trimming mechanism transversely byloosening the clamping bolts 205' and providing the transverseadjustment by means of the bolts 205. In this case '205' will throw theadjustment off by at least a fraction of ten-thousand'ths of an inch.The amount of wear thus introduced is shown on the indicator and it maybe corrected. It*will be seen from the foregoing that itis entirelypossible, in the event that the template is inclined, that the grindingoperation on the gear will be carried out away from avertical centerline.

This, however, will introduce no errors since the grinding wheel will betrimmed for accurate.

grinding in this off center condition.

Rigidly secured on the sub-base 200 area pair of vertically extendingposts 220 on which the trimmer frame 22l is vertically slidable. The

.frame 22I includes elongated bosses 222 to provide for a firm supportof the trimmer carriage 22! on the posts 220. Tapped bosses 223 areprovided on the bosses 222 for the reception of 22! we provide a pair oflinks 225 which are pivoted to a stud bolt 226. The lower end of thelinks 225 are slotted as indicated at 221 and the base 202 carriesclamping bolts 228 which The bolts. 228 may be loosened to permitvertical adjustment of the trimmer support 22I and may be tightenedafter such adjustment to assist in retaining the trim- .pinion 229mounted on a shaft having a squared end 229a for cooperation with asuitable tool or wrench. The posts 220 may be provided with justed byrotating the. shaft 229a carrying the pinion 229.

The trimmer support 22! includes a template supporting arm 230 which isin all important respects similar to the template supporting arm 10. ,Inthe modification illustrated in Figures 11 to 16, this templatesupporting arm includes a template T accurately located by means of apair of centering pins 23l, and clamped in-place by means of a clampingscrew 232. The template 3 T is secured to a block 233 which isvertically adjustable' in a slot 234 provided in the template support230. The block 233 has a tapped opening in its upper portion whichreceives an adjusting screw 235 which is retained against axialdisplacement by a cap 236. Rotation of the adjustlng screw 235 resultsin corresponding vertical adjustment of the template T.

As best seen in Figure 12, the trimmer frame 22I is provided with a pairof shafts 240 on which are mounted a pair of levers 24l terminating insleeve portions 242' which are adapted to support the trimmer shafts243. The'trimmer shafts 240 carry radiallyadjustable diamond elements245, as best indicated in Figure 15. These elements are mounted incarriers 248. An adjusting screw 246 is provided for effecting theradial adjustment of the diamond element 245 andafter adjustment theelement is clamped in adjusted positionby a set screw 241.

252 are provided, threaded into tapped openings in the carrier 248 andadapted to engage the seats 250. As will be evident if one of theadjusting screws-252 is loosened while the other is tightened, acorresponding circumferential adjustment of the carrier 248 relative tothe shaft 240 will be effected. This permits accurately aligning thediamond point on the diamond element 245 with the point of the followerF. As 'best seen in Figure 15, the carrier 248 is retained against axialmovement of the shaft 243- by rack teeth 22% for cooperation with thepinion.

means of a lock bolt 253 whichseats within an annular V.-shaped groove254 formed in the shaft 243.

- The followers F are likewise radially adjustable of the shaft 243, andin practice the point of each follower F will b adjusted to have thesame spacing from the axis of the shaft 243 as the point of the diamondelement 245. Means are provided for simultaneously actu ating both ofthe trimmer elements, and the mechanism for effecting this comprises apair of meshing gears 260 mounted on trimmer support 22l'. The gears aresecured against rotation to their respective mounting shafts 26I and theshafts 26l carry levers 262. The shafts 243 are each provided withlevers 263 which are secured thereto against rotation. -Interconnectingthe levers 263 and 262 are links 264 which transmit rotation from theshafts 26l to the shafts 243.

Springs 265 are provided, paralleling the links 264 for the purpose oftaking up lost motion. An actuating sleeve 2661s rigidly secured to oneofthe shafts 261 and has projecting there-' from an operating lever 261.

Means are provided for limiting the amplitude of. oscillation of theshafts 26l, and these-take the form of collars 268 and269 havingprojecting ears adapted to engage a stop pin 210. Collars tive to theshafts 26l and have means (not shown) for rigidly clamping them inadjusted position on the shaft. As will be evident from Figure 12, thisprovides means for limiting the amplitude of oscillation of the shaftandalso for definitely fixing the point at which said oscillation isterminated in each direction.

The sleeves 242 have attending ears 2" thereon which are adapted to beinterconnected by a tension spring 212, the spring being effective tourge the follower F inwardly toward the template T.

Inasmuch as the form of the template is not a portion of the circulararc, oscillation of the shafts 243 as a result of the operation of thelever 261 will result in a slight oscillation of the levers 2 about theaxes of the shafts-240.

In this embodiment of our invention as in the one previously described,the construction p o-r plished by feeding the .grinding wheel into thevides for adjustability of the parts so as to locate the center ofoscillation of the arms carrying the follower F and the diamond element245 substantially adjacent the average center of curvature of thetemplate F and hence of the surface being trimmed onto the grindingwheel. This adjustment is accompanied by an adjustment of the length ofthe arm of the follower F and of the diamond element 245 so as to makethese arms approximately equal to the average'z radius of curvatureof-the template and of the work being trimmed. As aresult of thisconstruction, the diamond element 245 will. always be substantiallyperpendicular to the surface being trimmed at the point of engagementtherewith, thus increasing the life of the diamond and increasing theaccuracy of the surface being trimmed. I

Adjustment of the axis of the shaft 243 to approximately the desiredposition relative to the of the trimmer support 22l as a whole, and acorresponding adjustment of the template T into alignment with thesurface being trimmed. This has the effect of raising or lowering theaxis of the shaft 243 relative to the template. The remainingadjustments necessary are the adjustment of the length of the diamondelement 245 radially of its carrier 248 previously described Y and asimilar adjustment of the follower -F.

In the present embodiment the axis 'of the major link of the system oflinkage is located on the same side of the template and of the workpiece as the follower and diamond point. In most cases this is anentirely satisfactory ardescribed.

While we have illustrated carrier 248 in detail only in conjunction withthe embodiment of our invention illustrated in Figures 11 to 16, it willbeunderstood that the same structure may, if desired, be employed in themodification ,illustrated in Figures 1 to 5. In the modificationillustrated in Figures 1 to 5, we have indicated a somewhat differentarrangement in -which the follower carrying member 98 with its sleeve 99is radially adjustable of the shaft 91, and seats 81' are'shown on theshaft in Figure 8 for cooperation with adjusting screws, similar tothose shown at 252 in Figure 14.

In like manner it will be understood that while 30 mechanism is made asfollows:

55 area. rangement, and the present construction which- I 268 and 259are independently adjustable relameans for adjusting the template in themodification illustrated in Figures 11 to 16, this may be identical withthat shown in-detail in Figures 8 and 9.

The trimmer mechanism may be associated with the grinding machine ifdesired so that the path traversed by the trimming points is directly inline with the work piece being ground. In this arrangement is provided,trimming is accomplished by traversing the grinding wheel into the-verticalplane of the trimming points, feeding the samedown to providestock for trimming, and performing the trimming operation. When thetrimming operation is complete, the wheel is traversed without furtherfeed in a vertical direcplane of the trimming points and feeding thesame vertically to proper position to provide material for removal bytrimming. After the trimming wheel is thus provided with properly shaped5 grinding surfaces, it may then be fed back to the proper verticalposition for grinding and traversed back to the vertical plane of thework to be ground.

In the last case, adjustment of the trimming The trimming assembly as awhole is adjusted vertically to locate the template approximately inline with the work. The trimming arm and the diamond carrying arm areadjusted radially of their com- -'35 mon shaft so that their lengths areapproximately equal to the average radius of curvature of the template,and hence of-the work to be trimmed respectively. The follower arm isthen allowed to engage the curved surface of the tem-' e 0 plate and isactuated to follow this curve while template is accomplished by verticaladjustment,

{ position for the parts and will result in the diamond carrying armmaintaining itself substantially perpendicular to the surface of thework at all times.

It may be stated at this time that commercial diamond trimming pointshave a diamond located substantially at their axes, but in many casesthis diamond is somewhat displaced from the axis,-and instead ofpresenting a theoretical point it will in most cases present a flatsurface of some Furthermore, while the diamond. is, of course, veryhard, it tends to wear out, and after a certain amount of usagethe'diamond doing the actual trimming presents a convex surface.

As emphasized in. the foregoing, the present trimmer is adapted to trimthe grinding wheel so as to reproduce curves on the work piece withinlimits of one or two ten-thousandths of an inch. Where the diamondtrimmer has worn and where no means are provided for swinging 5 thediamond carrying arm about an axis located approximately at the averagecenter of curvature of the surface being trimmed, different portions ofthe diamond are employed in different portions of an arc. This resultsin a departure or 7 error introduced between the point of the followerand the actual cutting point on the diamond trimmer. This in many casesintroduces an error sufllciently great to reduce the over-all accuracyof the grinding machine substantially.

we have not fully described the details of the .75 It.wlll beappreciated that if the follower and lars.

the diamond point could both be kept at a theoretical point, errors ofthis nature would not be the accurate adjustment of the machine set-up..

When a new diamond is provided, a considerable amount of time isrequired before the grinder is again in full production, due to thenecessity for testing the diamond and making such' adjustments as areshown to be necessary as a result of the tests.

It is found in practice that the diamond when employed with a mechanismof either of the foregoing embodiments will last, without replacement,several times as long as diamonds employed in conventional priortrimmers. This means that the production ofthe grinder need not beinterrupted for replacement of diamonds for a period several times aslong as that necessitated in prior trimmers. Furthermore, as explainedabove, the accuracy of the work is increased. 1

,While we have illustrated and described two specific embodiments of ourtrimming mechanisms, it will be understood that this has'been practicethe invention, the scope of which is indicated by the appended claims.

What we claim as our invention is: I 1. Trimming mechanism for grindingwheels comprising a base, a trimmer frame vertically adjustable on saidbase. ,a template support verv tically adjustable on said frame, a leverpivoted 'atone end to said frame, a shaft pivotally carried by theopposite end of said lever, a template follower adjustable radially ofsaid shaft, adiamond trimmer adjustable radially of said shaft, wherebysaid template support may be aligned with said grinding wheel, the axisof said shaft may be located adjacent the average center of curvature ofthe trimmer surface of said grinding wheel, and said template followerand diamondtrimmer may be spaced from the axis of said shaft by anamount substantially equal to the average radius of curvature of saidtrimmed surface.

' done solely to enable those skilled in the art to 2. A trimmercomprising a base having ver- 7 having a shaft housingadjacent theswinging end thereof, a shaft in said housing carrying a diamond and afollower at opposite ends, a stop carried by said housing at one end,and adjustable abutments carriedby said shaft for limiting rotation ofsaid shaft in said housing, said adjustable abutments comprising a pairof. col

lars having overlapping cut-away portions for receiving said stop, saidcollars being independently adjustable on said shaft,

5. In a trimmer, a rotatable shaft, a follower support and a' diamondsupport on opposite ends of said shaft, one of said supports comprisinga carrier rotatable on said shaft, said shaft having a pair of generallyradial seats thereon separated by a radial web providing a concentricbearing surface between said seats, and adjustable abutments onv saidcarrier engageable with said seats for adjusting said support about theaxis of said shaft.

6. In a trimmer, a rotatable shaft, a follower support and a diamondsupport on opposite ends of said shaft, one of said supports comprisinga carrier rotatable on said shaft, said shaft hav.-'

ing a pair of generally radial seats thereon separated by a radial webproviding a concentric bearing surface between said seats, said seatsfacing substantially in the same direction and adjustable abutments onsaid carrier engageable with said seats for adjusting said support aboutthe axisof said shaft.

7. A trimmer comprising a base; a frame vertically adjustable on saidbase, a pair of levers swingable about parallel axes on said frame, atemplate support, adjustable on said frame toward and' away from saidaxes, rotatable shafts carried by'the free ends of said levers, saidshafts having a template follower and a diamond trimmer at oppositeends.

8. A trimmer comprising a base, a frame vertically adjustable on said,base, a pair of levers swingable about parallel axes on said'frame, atemplate support adjustable on said frame toward and away from saidaxes, rotatable shafts carried by the free ends'of said levers, saidshafts having a template follower and a diamond trimmer at oppositeends, resilient means urging both of said levers into operativeposition, and latch means for retaining either of said levers ininoperative-position.

9. A trimmer comprising a base, a frame vertically adjustable on saidbase,,a pair of levers swingable about parallelaxes on said frame, atemplate support adjustable on said frame toward and away from saidaxes, rotatable shafts carried by the free ends of said levers, saidshafts having a templatefollower and, a diamond trimmer at oppositeends, resilient means urging both of said levers into operativeposition, and means for rotating both of said shafts about their axesincluding a single manually movable member a diamond trimmer foradjustment radially of said shaft. I

3. In a trimming mechanism, a swinging frame having a shaft housingadjacent the swinging end thereof, a shaft in said housing carryingadiamond and a follower at opposite ends, a stop andconnections betweensaidmember and each ofsaid shafts. I

10. A trimmer comprising a base, a frame vertically adjustable on saidbase, a pair of levers swingable about parallel axes on said frame, atemplate support adjustable on said frame toward ,and away from saidaxes, rotatable shafts carried by said housing at one end, andadjustable abutments carried by said shaft for limitcarried by the freeends of said levers, said shafts having a template follower andadiamondtrimmer at opposite ends, resilient means urging both of said leversinto operative position, and means for rotating both of said shaftsabout their axes including a pair of gears, a manually operable leverfor rotating one of said gears, and

connections between each of said gears and one of said template, wmeansurging both of said shafts toward said template support, and means forswinging either of said shafts away from said template support andlatching the same in inoperative position. i

12. Trimming mechanism for a grinder of the type having a horizontalwork slide, comprising a trimmer base on the slide, a frame verticallyadjustable on said base, a template vertically adjustable on said frame,a lever pivotally supported at one end on said frame, a shaft pivoted toa the other end of said lever, a trimming arm and a template followingarm on said shaft, both of said arms being radially adjustable of saidshaft, 1

whereby said template may be aligned with the in periphery of thegrinding wheel. the axis of said shaft locatedat the average center ofcurvature ofthe template, and following and trimming arms may beadjusted in length to equal the average radius of curvature of thetemplate.

FRANK PERNACK. WILLIAM A. SCHUL'I'E.

